BIEBER’S DROP-IN GUEST

Justin Bieber got a house call from Dr. Ehsan Ali last week. Paparazzi spied Ali slipping out the back door of the Biebs’ (inset) $55,000-amonth Beverly Hills mansion last Friday, but didn’t know his name or why he was there. We have learned that Ali, a prominent Beverly Hills physician, was the mystery doc. He’s known for administering customized vitamin IV drips to tireless performers, including Demi Lovato and Rita Ora.